Recently, a test system for an internal combustion engine has become increasingly complicated. For example, although test contents for a diesel engine are different from those for a gasoline engine, there has been developed a test system compatible for measuring both of the diesel engine and gasoline engine.
By the way, in the case of adopting such a large-scale test system, the number of test devices such as exhaust gas lines for the sampled exhaust gas to flow, switching valves or measurement equipment is also increased. Therefore, an operation error is likely caused by a user, and as a result, it becomes necessary to redo the test, and further this may even cause a damage of the test device or the internal combustion engine.
For example, in the case where an operation error has been done such that an internal combustion engine is driven without activating a blower for sucking exhaust gas, there may likely be a case where a filter of a dilution gas introduction pipe for diluting the exhaust gas may likely be burned.
Further, for the time of performing a flow rate verification of a blower or correcting a flow rate measurement value of dilution gas and the like, a shut-off valve is provided in the exhaust gas line for preventing the exhaust gas from flowing. In this configuration, if an internal combustion engine is operated while the shut-off valve remains closed, i.e., in a state that the exhaust gas does not flow in the exhaust gas line, there may likely be a case where the exhaust gas may flow back to the internal combustion engine, which may damage the internal combustion engine.
Alternatively, a sample bag is provided as a test device for sampling and batch-analyzing the exhaust gas. In this configuration, if gas is excessively fed in this bag, there may be a case where the bag is damaged. Since the PM collection filter is clogged in the case of collecting more than a certain amount of PM, it is necessary to clean or replace the PM collection filter.